2006-2009 Honda TRX680 (TRX 680 FA-FGA) Factory Service Manual, Page 216Get this manual
CYLINDER HEADIVALVECAMSHAFT Contact area (too high or too low)
- Reface the valve seat
TOO HIGH
REFACING
Follow the retecer manufacturer's operating instructions Be careful not to grind the seat more than necessay
If the contact area is too high on the valve, the seat must be lowered using 32 flat cutterIf the contact area is too Iowan the valve, the seat must be raised using 60 interior cutter